The light condenser or integrator used in LCD projectors harmonizes the beam and the source and converts the circular screen into a 4:3 or 16:9 rectangular screen. FIG. 1A and FIG. 1B show two common integrators.
As shown in FIG. 1A, the first array of lenses 20 divides the light beam from the light source 10 into multiple of 4:3 or 16:9 rectangular blocks and forms an image on the second array of lenses 30; then the second array of lenses 30 projects the image formed by the first array of lenses onto the display panel 40. In FIG. 1B, the light beam from light source 10 passes through the cylindrical glass integrator 25; emerges onto lens 35; and projects onto the display panel 40.
Most of the liquid crystal projectors (LCP's) use the characteristics of the polarized light to adjust the luminous intensity. However, this method has its disadvantages. To adjust the luminous intensity, only a certain direction of the polarized light from the light source 10 is illuminated. Thus, the rest of the polarized light energy is unused. Therefore, one of the effective solutions to improve the efficiency of the liquid crystal projector's luminous intensity is to reuse the energy of the previously unused polarized light.
Due to the restriction of the second law of thermodynamics, since the scattering angle and light radiated area increases when an unpolarized light is polarized, the resolution of the LCP decreases. Since increasing the light radiated area can cause problems for small LCP's, where a small arc length for the light source is preferred, instead of decreasing the area of the light beam, increasing the area of the light beam can also effectively polarize the light beam while the resolution of the LCP is maintained.
To overcome the problem mentioned above, a cylindrical integrated polarization converter was disclosed (R.O.C. Patent number 119661). By placing the incident surface of the cylindrical glasses at one focal point of the elliptical mirror, the light beam passes through the cylindrical glass and emerges to the converging lens and polarized light converter, to form an image on the display panel with appropriate light illumination. However, in a real application, an image array will be formed on the second lens. This makes the incident angle of the image array big and the size of the image array is not matched with the gap between the image array and the polarized light converter. As a result, the efficiency of the conversion of the polarized light is low and is unable to achieve the desired result.